The aim of this work was the morphological, physicochemical, mechanical and biological characterization of a new composite system, based on gelatin, gellan and hydroxyapatite, and mimicking the composition of natural bone. Porous scaffolds were prepared by freeze-drying technique, under three different conditions of freezing. The morphological analysis showed a homogeneous porosity, with well interconnected pores, for the sample which underwent a more rapid freezing. The elastic modulus of the same sample was close to that of the natural bone. The presence of interactions among the components was demonstrated through the physicochemical investigation. In addition, the infrared chemical imaging analysis pointed out the similarity among the composite scaffold and the natural bone, in terms of chemical composition, homogeneity, molecular interactions and structural conformation. Preliminary biological characterization showed a good adhesion and proliferation of human mesenchymal stem cells.

Over the past decade, a large number of strategies and technologies have been developed to reduce heart failure progression. Among these, cardiac tissue engineering is one of the most promising. Aim of this study is to develop a 3D scaffold to treat cardiac failure. A new three-block copolymer, obtained from δ-valerolactone and polyoxyethylene, was synthesised under high vacuum without catalyst. Copolymer/gelatine blends were microfabricated to obtain a ECM-like geometry. Structures were studied under morphological, mechanical, degradation and biological aspects. To prevent left ventricular remodelling, constructs were biofunctionalises with molecularly imprinted nanoparticles towards the matrix metalloproteinase MMP-9. Results showed that materials are able to reproduce the ECM structure with high resolution, mechanical properties were in the order of MPa similar to those of the native myocardium and cell viability was verified. Nanoparticles showed the capability to rebind MMP-9 (specific rebinding 18.67) and to be permanently immobilised on the scaffold surface.

Poly (L-lactide)-poly (oxyethylene)-poly (L-lactide) block copolymers obtained in bulk, by a ring opening mechanism, from poly(ethylene glycol)s (PEG)s and L-lactide (LA), at 120-140 degrees C, in the absence of added catalysts are described. By using PEGs with different molecular masses, 3000 and 35 000, respectively, and varying the initial molar ratio LA to PEG, two series of copolymers with different molecular masses, relative length of blocks and hydrophilicity were obtained. Physico-chemical characterization of the copolymers had been previously performed. The morphological characteristics of the copolymers were investigated by means of X-ray diffractometry, optical and scanning electron microscopy. The biological properties of the materials were determined by evaluating their cytotoxicity, cytocompatibility, hemocompatibility and degradability using different standard tests. The results obtained indicate that the block copolymers synthesized may be useful for biomedical applications, in particular as resorbable drug vehicles. The materials are brittle and their mechanical properties are not appropriate for implant devices

The radical polymerization of acrylic acid and sodium 4-styrenesulfonate in the presence of chitosan as a template gives insoluble products, identified as the polyelectrolyte complexes chitosan-poly(acrylic acid) and chitosan-poly(4-styrenesulfonate). Kinetic results do not permit to propose any mechanism in the first case, while suggest a ''pickup'' one in the second. The polyelectrolyte complexes have been characterized by FT-IR spectroscopy, X-ray diffractometry, optical and scanning electron microscopies, differential scanning calorimetry and thermogravimetric analysis. The results obtained indicate an ordered structure for the first complex, while the second one appears similar to that obtained by reacting the parent polymers. Therefore, the template polymerization technique appears advantageous only for the synthesis of the chitosan-poly(acrylic acid) complex. The thermal analysis shows that the complexes undergo two successive modifications on heating. FT-IR analysis demonstrates that the first process is an esterification between the hydroxyls of chitosan and the acidic groups of both daughter polymers; the second one appears to be an amidation of the chitosan ammonium groups only with the sulfonate groups

Composite materials were prepared by mixing in different proportions of hydroxyapatite (HA) and poly(epsilon-caprolactone-oxyethylene-epsilon-caprolactone) block copolymer (PCL-POE-PCL) to produce a new resorbable material for biomedical applications. This material has proved to be very interesting for production of periodontal membranes. Mechanical properties are linearly proportional to the amount of HA introduced. Fourier transform infrared (FTIR) investigations have pointed out that HA is able to influence some close epsilon-caprolactone molecules to start its homopolymerization giving PCL with an end chain ionic bonding. HA grains are therefore surrounded by a film of PCL which grants close connection of HA grains within copolymeric matrix. This interface bond with PCL is, however, an interesting occurrence for preparations of HA/PCL composites.